Electric motor



July 15 1924. 1,501,558

J. H. HUNT ELECTRIC MOTOR Patented July 1 5, 1924.

UNITED STATES PATENT OFFICE.

JOHN E. HUNT, OF DAYTON, OHIO, ASSIGNOR TO GENERAL MOTORS RESEARCH COR- PORATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE.

ELECTRIC MOTOR.

Application filed September 26, 1923. Serial No. 665,024.

To all whom it may concern:

Be it known that I, JoHN H. HUNT, a citizen of the United States of America, residing at Dayton, county of Montgomery,

'. and State of Ohio, have invented certain new and useful Improvements in Electric Motors, of which the following is a full, clear, and exact description.

This invention relates to a controlling device for an electric motor including a plurality of field windings which can be separately operated to cause the motor to function in a different manner.

The form of invention shown herein pro- 16 vides improvements in apparatus for controlling a reversible electric motor and for preventing racingther'eof when a load is suddenly removed, one form of such apparatus bein shown in the copending application of alph L. Lee and Mortimer W. Fish, Serial No. 664,828, filed Sept. 26, 1923.

Further objects and advantages of the present invention will be had from the following description, reference being had to the accompanying drawing wherein ferred embodiment of the present inve..- is clearly shown.

' In the drawin Fig. 1 is an enfiiew of the electric motor,

80 certain portions thereof being shown in section for the purpose of clearly illustrating the brush structures and the operating elements.

Fig. 2 is a diagrammatic showing of the operating elements of this device and their circuit connections.

Referring to the drawings the numeral 20 designates the motor casing shown in,

section. 21 represents the motor armature 40 having a commutator 22. A plate 23 is secured to the casing 20 in any suitable manner and acts as a supporting plate for the various brushes and other operating elements. The stationary brush 24 is sup- 45 ported by an arm 25 fulcrumed on the stud 26 secured to the plate 23. Fulcrumed also on the stud 26 is an arm 27 which supports the movable brush 28. A spring 29 having one end anchored to the arm 27 while its 50 other end is anchored to the arm 25 will, due to these connections tend to draw the brushes 24 and 28 into engagement with the .on the pin 38 w ich is secured to the 30 which carries a roller 31, the function of which will be described hereinafter.

Another movable brush 32 is supported on the arm 33 which in turn is fulcrumed on the stud 34 secured to the plate 23. This arm 33 is also provided with a projection 34 which, like the projection 30 of arm 27, carries a roller 35 for purposes to be described. The arm 33 has one end of a spring 36 anchored thereto, the other end of. said spring being anchored to the plate 23. This spring tends to move the brush 32 into engagement with the commutator 22.

The operatin element 37 is fulcrumed plate 23. This operating element includes two oppositely disposed cams 39 and 40, the former being adapted to engage with the roller 31, while the latter cam 40 is adapted to engage with the roller 35 of brush 32. A11 insulating block 41 is mounted on the operating element 37, and acts as a supporting means for the contact element 42. This contact element 42- includes portions 43 and 44, one projecting from one side of the plug 41 and adapted to engage with the brush 28, while the other portion 43 projects from the other side of the plug and is adapted to en age with the brush 32. The operating e ement 37 includes three. indents 45, 46 and 47 which act as receptacles for a roller 48 mounted on the arm 49 which is fulcrumed on a stud 50 secured to the plate 23. A spring element 51 interposed between the arm 49 and the plate 23 tends to hold the arm 49 in such a position where the roller 48 will always engage with the outer surfaces of the indents 45, 46 and 47 dependent of course upon the position of the operatin element 37. The operating element 37 15 provided with a handle 37? which projects through an opening 20 provided in the casing 20. By means of this handle 37 the operating element 37 may be shifted to its various positions.

Normally, that is, when the machine is not in operation, the handle 37 a will be in such a position where the roller 48 will rest in the indent 45, tending to hold this operating element 37 in the normal position. In this position the cam 39 will be in engagement with the roller 31 thereby holding the brushes 28 out of engagement with the commutator 22 against the action of the spring 29, also the cam 40 will be in engagement brush 28 into commutator engagement. The

with the roller 35 and thus hold the brush 32 portion 43 of the contact element 42 will be brushes 28 or 32 to cause operation of the out of engagement with the commutator disengaged from the brush 32 and the conagainst the action of the spring 36. Now tact portion 39 will be moved into engagewhen it is desired to operate the motor either ment with the brush 28 thereby bringing the in one direction or the other the operator resistance unit 60 into circuit connections may shift the handle 37 in either direction With the field'71 producing opposite rotathereby bringing into efl'ect either one of the tion of the armature.

While the form of embodiment of the inmotor. Supposing that the operator shifted vention as disclosed constitutes a preferred the handle to the left as shown in Fig. 1, form, it is to be understood that other forms the operating element 37 would. be moved might be adopted, all coming within the about its fulcrumed point 38 in a counterscope of the claims which follow.

clockwise direction moving the indent por- What I claim is as follows tion 45 away from the roller 48 while at the 1. An electric motor comprising in combisame time moving the cam 40 away from the nation, a plurality of field windings; a reroller 35 carried by the arm 33. This would sistance element; a commutator; a stationpermit the spring 36 to move the brush 32 ary brush; movable brushes each connected into engagement with the commutator 22. with a field winding; resilient means for The contact portion 43 would be moved into moving said brushes into engagement with engagement with the upper surface of the the commutator; and an operating element brush 32 and thereby close circuit connecadapted normally to hold the movable tions between the resistance element 60 which brushes out of commutator engagement but 'is connected to the contact element 42 and operable to permit the resilient means to the field 70 shown in the diagrammatic view move one of the brushes into commutator of Fig.2 only. The operating element 37 engagement and at the same time connect I will be held in this position, due to the fact the resistance unit in parallel with the comthat the roller 48 is rigidly held in this inmutator engaging brushes.

dent 46, due to the action of the spring 51 2. An electric'motor comprising-in combiassociated with the arm 49 which carries the nation, two field windings for 'producin roller 48. In this position the cam 39 of the opposite magnetic, effects; a movable brus operating element 37 will still engage the connected to "each field; a-commutator; a roller 31 thus holding the arm 27 in such a stationary brush; a resistance element; position where the brush 28 will be out of springs for moving the movable brushes into engagement with the commutator 22.

By referring to the Fig. 2 the circuit connections of the motor in'this position can be traced from themain feed line 61 current flowing to the stationary brush arm 25 then brush 24 to the commutator 22 through the armature 21 to the brush 32 (which is shown in disengaged position in this figure) thence throu h the field to the opposite feed line 62. urrent will also flow from the main feed line 61 through the resistance winding 60'to the contact element 42thence through the portion 43 of contact element to the brush 32 and thencethrough arm 33 to the field winding 70. By connecting the 'resistance winding 60 in parallel with the armature, the tendency I of the motor to overrun when the load on the motor is removed, is substantially reduced. The presence of the resistance unit 60 will not aflect the torque or the speed to any objectionable extent in the speed rangein which the useful work of the motor is obtained.

It will of course be understood that when it is desired to reverse the operation of the motor the operator shifts the handle 37 to the ri ht as regards Fig. 1 causing the brush 32 to %e lifted by the cam 40 and causing the cam 39 to be moved away from the roller 31 of brusharm 27 thereby permitting the o eration 29 to come into eifect to move t e commutator engagement; an element normally holding the brushes out of engagement with the commutator and operable to permit either one of the brushes to be moved into commutator engagement; and circuit controlling means associated with the element for connecting the resistance winding in circuit with the armature when one of the fields is connected to the armature.

3. An electric motor comprising in-combination, two field circuits'each includinga separate movable brush; a stationary brush; a commutator; a-resistance element; springs for moving the brushes into commutator engagement; an operating element normally holding the movable brushes out of engagement with the commutator and operable to ermit either one of the movable brushes to e moved into commutator engagement while the other is held out of enga ement therewith; and a contact associate with the perating element and the resistance winding and adapted to engage with either one of the movable brushes when it is moved into'commutator engagement, to connect the resistance winding to the brush so affected.

4. An electric motor comprising in combi: nation, two field windings each havin ciated therewith a separate movable a stationary brush; a commutator; a resistance element; springs for movingthe assorush;

brushes into engagement with the commutator; an operating element normally holding the movable brushes out of commutator engagement but operable to selectively permit either one of the movable brushes to be moved into engagement with the commutator and to maintain the other brush in normal position; a contact mounted on the operating element and connected to the resistance winding and adapted to engage with the movable brush that is moved into commutator engagement; and means for maintaining the operating element in its various positions.

5. An electric motor comprising, in combination, a commutator, separate field windings, brushes each connected with a field winding and movable into or out of engagement With the commutator, an armature circuit connected with the commutator, a resistance element, and means for causing the movable brushes to engage the commutator separately and with yielding pressure and to cause the resistance element to be connected in circuit with that field winding then connected with the armature, or for causing the said movable brushes to be removed from the commutator and the resistance element to be disconnected from the motor.

In testimony whereof I hereto aifix my signature.

JOHN H. HUNT. 

